TOI-2076 d
Astrophysical Synthesis & Habitability Characterization
TOI-2076 d is a confirmed sub-neptune exoplanet orbiting the star TOI-2076, located approximately 136.7 light-years (41.91 parsecs) from the Solar System. First announced in 2021 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1564% across the stellar disk), this world measures 3.27 Earth radii (0.29 Jupiter radii) and has a measured mass of 7.3 Earth masses. Combining its mass and radius yields a mean bulk density of 1.15 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.68 g⊕ (6.67 m/s²), and an escape velocity of 16.7 km/s.
In its orbital architecture around TOI-2076, TOI-2076 d completes one full revolution every 35.128 Earth days at a semi-major axis of 0.1982 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 61.4 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.027 (ranging from 0.1928 AU at periapsis to 0.2036 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 490 K (+217°C / +423°F) and receiving 16.50 S⊕ (~22,457 W/m²), TOI-2076 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-2076 is classified as an orange K-type star of spectral type K V with an effective photospheric temperature of 5,187 K, a radius of 0.758 R☉, a mass of 0.849 M☉, an estimated bolometric luminosity of 0.373 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.21 Gyr and a metallicity of [Fe/H] = -0.09 dex (near-solar heavy-element abundance). From Earth, TOI-2076 shines at apparent V-band magnitude 9.139 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The TOI-2076 system is a multi-planet architecture hosting 4 confirmed worlds, with TOI-2076 d sharing its stellar neighborhood alongside TOI-2076 e, TOI-2076 b, TOI-2076 c.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-2076 |
| Spectral Type | K V |
| Effective Temp (Teff) | 5,187 K |
| Stellar Radius | 0.7580 R☉ |
| Stellar Mass | 0.8490 M☉ |
| Bolometric Luminosity | 0.373 L☉ |
| Metallicity [Fe/H] | -0.090 dex |
| Stellar Age | 0.210 Gyr |
| Apparent Magnitude | V: 9.139 · G: 8.910 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.198200 AU |
| Orbital Period | 35.128 days |
| Mean Orbital Velocity | 61.4 km/s |
| Orbital Eccentricity (e) | 0.02700 |
| Orbital Inclination (i) | 89.1640° |
| Mean Bulk Density | 1.15 g/cm³ (16.7 km/s vesc) |
| Insolation Flux | 16.5000 S⊕ (~22,457 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 136.700 LY (41.909 pc) |